1. Field of the Invention
The present invention relates to a silver halide photographic emulsion having high sensitivity and excellent latent image keeping characteristics and a silver halide photosensitive material using thereof.
2. Description of the Related Art
It is well known generally to use tabular silver halide grains (hereinafter, called as “tabular grains”) for obtaining a silver halide photosensitive material having high sensitivity. As the sensitization process of these tabular grains, a sensitization process using epitaxial splice is disclosed (for example, Jpn. Pat. Appln. KOKAI Publication No. (hereinafter referred to as JP-A-)8-69069 and JP-A-2002-278007).
The epitaxial sensitization process disclosed in these patents is a process by which silver halide having comparatively high silver halide content rate is epitaxially spliced with host tabular grains mainly having silver iodobromide.
However, although high sensitivity can be obtained by the epitaxial flat plate, performance is not always stable and it cannot be said that it is suitable for stably obtain performance as a photosensitive material. It is caused by that since the solubility product of silver chloride is larger than the solubility product of silver iodide, halogen conversion between the epitaxial protrusion portions of host grains occurs easily. Consequently, a photosensitive material using the epitaxial flat plate has a problem that the lowering of sensitivity and fog increase at storage occur easily.
In order to improve the stability of the epitaxial flat plate, there is disclosed an epitaxial flat plate having silver halide in which the main compositional component of host grains and the epitaxial flat plate is silver bromide (JP-A-2003-15245).